Figure 8

Induction of antigen-specific CD8⁺ T cell responses by mRNA-electroporated mature IL-15 DCs. Short-term cultured IL-15 DCs were matured with our TLR7/8 agonist-based maturation cocktail (TLR-mDC), electroporated with mRNA encoding the influenza virus matrix protein M1 and cocultured with autologous PBLs for 6 days. (a) The expansion of M1-tetramer binding CD8⁺ T cells was determined by flow cytometry. The lower dot plot represents the observed percentage of M1-tetramer⁺ CD8⁺ T cells in one representative donor (n = 4; mean ± SEM percentage of M1-tetramer⁺ CD8⁺ T cells: 4.4 ± 2.9). Correct positioning of the M1-tetramer⁺ CD8⁺ gate was defined by the respective negative control, as exemplified in the upper dot plot. (b) Simultaneously, a fraction of the PBL was harvested and stimulated with an irrelevant HLA-A*0201-restricted peptide (CEA) or rechallenged with the immunodominant influenza matrix protein (M1). The mean ± SEM percentage of antigen-specific IFN-γ⁺ CD8⁺ T cells was determined by ICS, as specified in the "Methods" section (n = 4; *, P = 0.03).